Just got me a Cordless Desktop (or Freedom, for you yanks... 😛) Optical. Range is stated as 6ft on these thigns, but its very environment dependant. I wanted it to be asble to get used from anywhere in my room, and since its a long room and the comp is at one of the ends, it was unlikely to be happenin...indeed, the range falls just a couple ft away from where wanted it....my solution, i bought a 3m USB extension cable, and now run both mouse and keyboard off the single USB connection (leaving the PS2 ports free for my old keyboard and the main mouse i use, the Intellimouse Explorer 3), and put the reciever effectively behind where i normally use the thigns, but thus extending the range quite a bit (even more because it got it away from my monitors...).
At 10ft, its quite probable it will just be good enough without an extension, bu as i said, depends on the environment its in.